The present invention relates to the field of motor vehicle brakes. More precisely, the invention relates to an improved construction of a subassembly of a brake actuator which is provided for an electromechanically operated parking brake or an electromechanically operated service brake.
Electrically operated parking brakes are used increasingly often in motor vehicles. They have the advantage that they can be controlled with modern on-board electronic systems, thereby opening up new possibilities for the use of parking brakes in a motor vehicle. For example, by electronically controlling such a parking brake, it is possible to prevent undesirable backward rolling when starting on an incline or quite generally the opening of the parking brake can be made dependent on an appropriate operating point of the vehicle motor.
An electrically operated parking brake generally comprises an electromechanical brake actuator, which applies a closing clamping force to a wheel brake by means of a spindle gear and an axially displaceable brake piston. In this case the brake actuator is substantially defined by a subassembly which comprises motor and gear units and which is arranged in a damping manner in a housing. A particular challenge involves providing a powerful brake actuator which supplies the necessary closing clamping force to the wheel brake and is simultaneously constructed in a compact manner in order to save space and weight. Therefore, there is often used a multiple-stage planet gear which is distinguished by a compact construction and a high reduction of the rotational movement produced by the electric motor.
From patent application WO 2004/044445 A2 an electromechanical brake actuator is known which has an electric motor and a gear unit for generating and transmitting a torque. In this instance, a two-stage planet gear is used. The electric motor and components of the gear unit are orientated relative to each other on an auxiliary frame and are received in a damping manner in a housing. An internal-toothed wheel acting as a central component of the planet gear is arranged in a damping manner at a plurality of locations on the housing and on the auxiliary frame.
The stable mechanical fixing of the gear components of an electromechanical brake actuator is decisive in order, on the one hand, to reduce the volume and the weight of the brake actuator and, on the other hand, to increase its service-life. For example, already an external damage to the housing may result in the operational failure of the gear unit if it is supported directly on the housing.